RE: Defining a radioactive isotope as source

From: Joachim Vollaire <joachim.vollaire_at_cern.ch>
Date: Tue, 24 Apr 2012 20:23:57 +0000

Dear Mina,

1) Does the first method, i.e. using the HI-PROPE option, do the same, i.e. use isotropic and mono-energetic gammas with
energy as the average energy of (1332.5 keV and 1173.2 keV)?

Yes in theory both approach should be the same if you are careful with the normalization. Using the built-in source is however more
straightforward, e=
specially for isotopes with many gamma lines... In the case of Co you could do one photon run with one energy and another one with
the other line. As =
the results are normalized per primary, you would need to add the scored quantity of the two runs and then multiply per the Co60
activity as one disin=
tegration leads to the production of two photons....

2) Can the activity of the radioisotope be incorporated in the source definition?
If you use the built-in source, the results are normalized to one disintegration. This mean than when you post process the results
you have to normalize to the activity, as for a "prompt" calculation where results are normalized to one primary particle....

3) Is it possible to define multiple radioisotopes as sources, taking into account activities of each?

The best is to run independent calculations for each isotopes, then normalize to the corresponding activity (see 2) above) and add
the results....

More general comment, you must not forget to call the particle decay with RADDECAy for ISOTOPE used with the BEAM card. I have
attached below some car=
ds taken from a calculations where I was looking at the dose rate from Ar41 decay in air in a 300 X 300 X 300 cm3 room. The specific
activity in the a=
ir was equal to 70 kBq/m3, thus to get the results in microSv/h the normalization factor I was using is the following :

(3600/1.0e06)*3*3*3*70e3

*
BEAM 1.0ISOTOPE
BEAMPOS 0.0 300.0 0.0 300.0 0.0 300.0CART-VOL
BEAMPOS 0.0 0.0 0.0
*
HI-PROPE 18. 41.

DCYSCORE -1.0 0. 0. DR-001 DR-001 USRBIN
*
*
USRBIN 10.0 DOSE-EQ -45.0 200.0 20.0 200.0DR-001
USRBIN -200.0 -20.0 -200.0 100.0 1.0 100.0&

Hoping this help

Joachim

-----Original Message-----
From: owner-fluka-discuss_at_mi.infn.it [mailto:owner-fluka-discuss_at_mi.infn.it] On Behalf Of Mina Nozar
Sent: 24 April 2012 03:12
To: fluka-discuss_at_fluka.org
Subject: Defining a radioactive isotope as source

Hello everyone.

I have a couple of questions in regard to how radioactive isotopes (as sources) are handled in FLUKA.

Looking through the "Sources" slides under
http://www.fluka.org/fluka.php?id=3Dcourse&sub=3Dprogram&navig=3D2&which=portugal2010

To set up Co-60 as the radioactive source, it seems there are two options.
One through the use of the "BEAM -> ISOTOPE" and "HI-PROPE -> Co-60 A,Z settings" and
another through the use of the "BEAM -> average energy for the two main gamma energies emitted by Co-60".

1) Does the first method, i.e. using the HI-PROPE option, do the same, i.e. use isotropic and mono-energetic gammas with
energy as the average energy of (1332.5 keV and 1173.2 keV)?

2) Can the activity of the radioisotope be incorporated in the source definition?

3) Is it possible to define multiple radioisotopes as sources, taking into account activities of each?

Thank you,
Mina
Received on Wed Apr 25 2012 - 15:33:39 CEST

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